The present invention relates to platinum group metal catalyzed addition-curable silicone adhesive compositions employing a bis(trialkoxysilyl)alpha-amino ester as an adhesion promoter.
As shown by Kasuya, U.S. Pat. No. 3,284,406, the adhesion of a cured platinum catalyzed addition-curable silicone composition onto a substrate can be achieved by effecting the cure of the silicone composition at a temperature such as 120.degree. C. for at least one hour.
Schulz, U.S. Pat. No. 4,087,585 is directed to self-adhering addition-curable silicone compositions which cure at 100.degree. C. after several hours and at temperatures up to 150.degree. C. for shorter cure periods. Satisfactory adhesion is shown on metallic substrates, such as aluminum, as a result of using an expoy-containing alkoxysilane as an adhesion promoter.
It would be desirable to provide addition-curable silicone adhesive compositions which could be applied onto a variety of unprimed substrates, such as plastic or metal, to effect a satisfactory cure in about an hour and at a temperature of about 100.degree. C. or less. In addition, it also would be desirable to produce a silicone substrate composite having a silicone layer which would fail cohesively instead of adhesively when tested. As used hereinafter, the expression "adhesive failure" means the silicone layer can be cleanly separated from the substrate, while in a "cohesive failure", rupture can occur in the silicone layer or in the substrate when separation is achieved.